FORAGING BEHAVIOR AND DIET OF LACTATING FEMALE SOUTHERN SEA LIONS (OTARIA-FLAVESCENS) IN THE FALKLAND ISLANDS

This study investigated the foraging behaviour, diving behaviour, move ments and diet of lactating southern sea lions in the Falkland Islands . They appeared to be primarily nocturnal, benthic foragers hunting at depths ranging from the surf line down to 250 m, and from just off th eir breeding sites out to 45 km offshore. Occasional longer trips may extend foraging ranges to over 150 km from breeding sites. Attendance patterns suggest that Falklands' sea lions do not haulout simply to fe ed their pups. Other factors such as predation and thermoregulation ma y cause them to come ashore. When at sea they travelled at approximate ly 1 ms(-1), slower than previous studies of otariids indicated. Absen ce from the breeding site did not imply continuous foraging; all study animals used remote haulout sites away from their pups. Repeated use of the same areas and the short duration of foraging trips suggest tha t they were able to catch enough food within a fairly small foraging r ange. Data on diet support the suggestion that lactating sea lions are mainly benthic foragers. They take a wide range of prey species. The most common cephalopods were Loligo gahi, similar in size to those tak en by the fishery. There is therefore potential for competition betwee n the sea lion population and the Loligo trawl fishery. There was cons iderable overlap between the diet of sea lions and those of Gentoo and Magellanic penguins, which suggests that sea lions may compete with b oth species.